Looks interesting. There's just a little contradictory in the website. In the header it says "[...] much simplier alternative to XSLT [...]". And in the footer "[...] not intended to be a replacement of XSL [...]"...
Looks really promising. I think i will give it a try. I am currently using a combination of Markdown and LaTeX (Markdown with embedded LaTeX expressions for math, compiled using pandoc [1]). Do you have any concerns regarding stability or output quality precompiling this combination with PreTeX? In other words: Does PreTeX only precompile statements surrounded by "$" or "$$"?
What the actual... Either have multiple displays on your desk or take your laptop with you. I really enjoy not to take tons of stuff with me every day.